Disposable absorbent article comprising a durable hydrophilic topsheet

ABSTRACT

A disposable absorbent article comprising a durable, hydrophilic substantially liquid pervious topsheet, the substantially liquid pervious topsheet comprising:  
     (a) a topsheet substrate; and  
     (b) a hydrophilicity boosting composition coated on the substrate, the hydrophilicity boosting composition comprising a hydrophilicity boosting amount of nanoparticles,  
     wherein said nanoparticles have a particle size of from about  1  to about  750  nanometers. Methods of preparing disposable absorbent articles are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/446,297, filed Feb. 10, 2003.

FIELD OF THE INVENTION

[0002] The present invention relates to disposable absorbent articlecomprising a durable hydrophilic topsheets and methods of producingsame.

BACKGROUND OF THE INVENTION

[0003] Disposable absorbent articles such as diapers and adultincontinence products are well known in the art. Such disposablearticles collect and retain urine and fecal material deposited thereonby the wearer.

[0004] Nonwoven fabrics made of synthetic fibers and/or natural fibersare commonly used in absorbent articles, for example, as topsheetmaterial or as core wrap to enclose the storage layer of the absorbentcore. Such nonwoven fabrics are usually hydrophobic. However, for manyapplications in hygiene products it is necessary to have hydrophilicnonwoven. Therefore the nonwoven fabric has to be treated accordingly.

[0005] One typical component of disposable absorbent articles istopsheets. A topsheet is typically a nonwoven material designed toprovide an interface between the wearer and the absorbent core of adisposable absorbent articles as well as providing the first point ofcontact for any bodily waste exuded by the wearer. They may be a film,or more typically they are a nonwoven material which has been renderedhydrophilic.

[0006] A common method for rendering nonwoven fabrics hydrophilic iscoating the surface of the nonwoven with hydrophilic surfactants. Asthis coating does not lead to a tight chemical bond between the nonwovenand the surfactant, the surfactant can be washed off during use when theabsorbent article is wetted. The decrease in liquid strike-through timeis a desirable effect when the nonwoven is coated with surfactant.Liquid strike-through refers to liquid passing through the nonwovenfabric with liquid strike-through time referring to the time it takesfor a certain amount of liquid to pass through the nonwoven. However, asthe surfactant is washed off when coated nonwoven fabrics are exposed tothe liquid, the strike-through time in the next gushes is increased.This results in performance reduction during use on diapers or otherarticles comprising such nonwoven fabrics. Furthermore, at the same timeas liquid strike-through time decreases due to use of surfactants,surface tension of the liquid, which was in contact with the nonwovenfabric, is reduced. This reduction is undesirable, because it can causeincreased urine leakage in a diaper.

[0007] Another common method to render a nonwoven fabric or filmshydrophilic is by applying corona and/or plasma treatment. Plasma is anionized form of gas that can be obtained by ionizing a gas or liquidmedium. Plasmas are widely used for the treatment of organic andinorganic materials to promote adhesion between various materials.Polymers that have chemically inert surfaces with low surface energiesdo not allow good coatings with bondings and adhesives. Thus, thesesurfaces are treated to make them receptive to bonding with othersubstrates, coatings, adhesives and printing inks.

[0008] However, corona and plasma treatments lead to low coatingdurability upon storage of the treated material, i.e., hydrophilicitydecreases over time.

[0009] Thus, there is a need for a hydrophilic coating of a nonwoven,which is durable upon storage, is not easily washed off when wetted andallows the nonwoven to achieve fast liquid strike-through in multipleexposures to liquid.

SUMMARY OF THE INVENTION

[0010] A first aspect of the present invention provides a disposableabsorbent article comprising a durable, hydrophilic substantially liquidpervious topsheet, the

[0011] (a) a topsheet substrate; and

[0012] (b) a hydrophilicity boosting composition coated on thesubstrate, the hydrophilicity boosting composition comprising ahydrophilicity boosting amount of nanoparticles, wherein saidnanoparticles have a particle size of from about 1 to about 750nanometers.

[0013] A second aspect of the present invention provides a process formaking a disposable absorbent article comprising a durable, hydrophilicsubstantially liquid pervious topsheet, said process comprising the stepof:

[0014] coating a topsheet substrate with a hydrophilicity boostingcomposition, the hydrophilicity boosting composition comprises ahydrophilicity boosting amount of nanoparticles, wherein thenanoparticles having a particle size of from about 1 to about 750nanometers.

[0015] It should be understood that every limit given throughout thisspecification will include every lower or higher limit, as the case maybe, as if such lower or higher limit was expressly written herein. Everyrange given throughout this specification will include every narrowerrange that falls within such broader range, as if such narrower rangeswere all expressly written herein.

[0016] All documents cited are, in relevant part, incorporated herein byreference; the citation of any document is not to be construed as anadmission that it is prior art with respect to the present invention.All percentages, ratios and proportions are by weight, and alltemperatures are in degrees Celsius (° C.), unless otherwise specified.All measurements are in SI units, unless otherwise specified.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] While the specification concludes with claims which particularlypoint out and distinctly claim the present invention, it is believedthat the present invention will be better understood from the followingdescription of preferred embodiments, taken in conjunction with theaccompanying drawing wherein:

[0018]FIG. 1 is a partial cut-away top plan view of a disposableabsorbent article including a durable, hydrophilic substantially liquidpervious topsheet.

[0019]FIG. 2 is a schematic side view of a process for forming anabsorbent article according to the present invention.

[0020]FIG. 3 is a schematic top view of a strike-through plate which maybe used to measure Liquid Strike-through of a substrate.

[0021]FIG. 4 is a sectional view along 4-4 of the strike-through plateof FIG. 3.

[0022]FIG. 5 is a sectional perspective view along 5-5 of thestrike-through plate of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The term “coating”, as used herein, includes coatings thatcompletely cover a surface, or portion thereof (e.g., continuouscoatings, including those that form films on the surface), as well ascoatings that may only partially cover a surface, such as those coatingsthat after drying leave gaps in coverage on a surface (e.g.,discontinuous coatings). The later category of coatings may include, butis not limited to, a network of covered and uncovered portions anddistributions of nanoparticles on a surface which may have spacesbetween the nanoparticles. In some embodiments, the coating preferablyforms at least one layer of nanoparticles on the surface which has beencoated, and is substantially uniform. However, when the coatingsdescribed herein are described as being applied to a surface, it isunderstood that the coatings need not be applied to, or that they coverthe entire surface. For instance, the coatings will be considered asbeing applied to a surface even if they are only applied to modify aportion of the surface.

[0024] The term “hydrophilic” describes fibers or surfaces of fibers,which are wettable by aqueous fluids (e.g., aqueous body fluids)deposited on these fibers. Hydrophilicity and wettability are typicallydefined in terms of contact angle and the strike-through time of thefluids, for example through a nonwoven fabric. This is discussed indetail in the American Chemical Society publication entitled “ContactAngle, Wettability and Adhesion”, edited by Robert F. Gould (Copyright1964). A fiber or surface of a fiber is said to be wetted by a fluid(i.e., hydrophilic) when either the contact angle between the fluid andthe fiber, or its surface, is less than 90°, or when the fluid tends tospread spontaneously across the surface of the fiber, both conditionsare normally co-existing. Conversely, a fiber or surface of the fiber isconsidered to be hydrophobic if the contact angle is greater than 90°and the fluid does not spread spontaneously across the surface of thefiber.

[0025] As used herein, the term “hydrophilicity boosting” means acomposition when coated on a topsheet substrate to make a durable,hydrophilic substantially liquid pervious topsheet, produces a durable,hydrophilic substantially liquid pervious topsheet which has a liquidstrike- through time for the first gush of less than or equal to about 6seconds, more preferably less than or equal to about 4 seconds, and hasa liquid strike-through time for the fifth gush of test liquid, ofpreferably less than or equal to about 6 seconds, more preferably lessthan or equal to about 4 seconds, when tested in accordance with theStrike-Through Test in the Test Methods section and further describedherein.

[0026] As used herein, the term “comprising” means that the variouscomponents, ingredients, or steps can be conjointly employed inpracticing the present invention. Accordingly, the term “comprising” isopen-ended and encompasses the more restrictive terms “consistingessentially of” and “consisting of”.

[0027] The disposable absorbent articles of the present inventioncomprise a durable, hydrophilic substantially liquid pervious topsheet.Examples of illustrative disposable absorbent articles, include but arenot limited to, diapers, adult incontinence products, training pant,feminine hygiene pads, panty liners and the like. The durable,hydrophilic substantially liquid pervious topsheet comprises a topsheetsubstrate which has been coated with a hydrophilicity boostingcomposition. The substrate, and hydrophilicity boosting composition areboth exemplified in more detail herein.

[0028]FIG. 1 is a plan view of a disposable absorbent article,specifically a diaper 20, which is a preferred embodiment of anabsorbent article according to the present invention. The diaper isshown in its flat out, uncontracted state (i.e., without elastic inducedcontraction). Portions of the structure are cut away to show theunderlying structure of the diaper 20, especially the absorbent core 10.The portion of the diaper 20 that contacts a wearer is facing theviewer. The chassis 22 of the diaper 20 in FIG. 1 comprises the mainbody of the diaper 20. The chassis 22 comprises an outer coveringincluding a durable, hydrophilic substantially liquid pervious topsheet24 and/or a liquid impervious backsheet 26. The chassis may also includemost or all of the absorbent core 10 encased between the topsheet 24 andthe backsheet 26.

[0029] For unitary absorbent articles, the chassis 22 comprises the mainstructure of the diaper with other features added to form the compositediaper structure. While the topsheet 24, the backsheet 26, and theabsorbent core 10 may be assembled in a variety of well-knownconfigurations, preferred diaper configurations are described generallyin U.S. Pat. No. 5,569,234 entitled “Disposable Pull-On Pant” issued toBuell et al. on Oct. 29, 1996; and U.S. Pat. No. 6,004,306 entitled“Absorbent Article With Multi-Directional Extensible Side Panels” issuedto Robles et al. on Dec. 21, 1999.

[0030] The topsheet 24 in FIG. 1 may be fully or partially elasticizedor may be foreshortened to provide a void space between the topsheet 24and the absorbent core 10. Exemplary structures including elasticized orforeshortened topsheets are described in more detail in U.S. Pat. No.5,037,416 entitled “Disposable Absorbent Article Having ElasticallyExtensible Topsheet” issued to Allen et al. on Aug. 6, 1991; and U.S.Pat. No. 5,269,775 entitled “Trisection Topsheets for DisposableAbsorbent Articles and Disposable Absorbent Articles Having SuchTrisection Topsheets” issued to Freeland et al. on Dec. 14, 1993.

[0031] The topsheet 24 comprises a topsheet substrate (or substrate)which has been coated with a hydrophilicity boosting composition whichcontains nanoparticles 75. The substrate may be a nonwoven, a polymericfilm or combinations thereof. The substrate, hydrophilicity boostingcomposition, the nonwoven, and the porous polymeric film are allexemplified in more detail herein.

[0032] The durable, hydrophilic substantially liquid pervious topsheetof the present invention provides a substrate which has both an extendedshelf life and wear life. Prior high-energy treatments tended to have ashort shelf life. That is, during the time from purchase to ultimate useand disposal by the consumer the substrate would trend to loose itshydrophilicity. Surfactant treatments, such as those of the prior art,on the other hand would often have an adequate shelf life, but have aninadequate wear life. That is, upon contact with bodily fluids, such asurine, the substrate would instantly being to loose its hydrophilicproperties. This may even lead to a surface which repels the bodilyfluids it is designed to absorb even though the absorbent article hasnot reached its total absorbance capacity.

[0033] The durable, hydrophilic substantially liquid pervious topsheetof the present invention suffers neither of these limitations as thesubstrates treated with the hydrophilicity boosting composition of thepresent invention have a long shelf life and long wear life, that is thehydrophilic properties of the core wrap are not substantially lost overtime or upon contact with bodily fluids such as urine.

[0034] In one optional embodiment of the present invention the durable,hydrophilic substantially liquid pervious topsheet has a wash-offsurface tension of greater than about 65 mN/m, when tested in accordancewith the Determination of surface tension Test in the Test Methodssection and further described herein.

[0035] In another optional embodiment of the present invention thetopsheet substrate is a so-called SSS material, comprising a severallayers of spunbonded materials. SSS materials are exemplified in moredetail herein.

[0036] The backsheet 26 in FIG. 1 is generally the portion of the diaper20 positioned with the absorbent core 10 between the backsheet 26 andthe topsheet 24. The backsheet 26 may be joined with the topsheet 24.The backsheet 26 prevents the exudates absorbed by the absorbent core 10and contained within the article 20 from soiling other external articlesthat may contact the diaper 20, such as bed sheets and undergarments. Inpreferred embodiments, the backsheet 26 is substantially impervious toliquids (e.g., urine) and comprises a laminate of a nonwoven and a thinplastic film such as a thermoplastic film having a thickness of about0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Suitable backsheetfilms include those manufactured by Tredegar Industries Inc. of TerreHaute, Ind. and sold under the trade names X15306, X10962, and X10964.Other suitable backsheet materials may include breathable materials thatpermit vapors to escape from the diaper 20 while still preventingexudates from passing through the backsheet 26. Exemplary breathablematerials may include materials such as woven webs, nonwoven webs,composite materials such as film-coated nonwoven webs, and microporousfilms such as manufactured by Mitsui Toatsu Co., of Japan under thedesignation ESPOIR NO and by EXXON Chemical Co., of Bay City, Tex.,under the designation EXXAIRE. Suitable breathable composite materialscomprising polymer blends are available from Clopay Corporation,Cincinnati, Ohio under the name HYTREL blend P18-3097.

[0037] Diapers 20 according to the present invention may be providedwith a re-closable fastening system (not shown) or may alternatively beprovided in the form of pant-type diapers.

[0038] The diaper 20 may also include such other features (not shown) asare known in the art including front and rear ear panels, re-closablefastening system, lotion, waist cap features, pant type diapers,elastics and the like to provide better fit, containment and aestheticcharacteristics. Additional illustrative, but non-limiting, informationon construction, assembly, and the various components of disposablediapers may be found in U.S. Pat. No. 3,860,003 to Buell; U.S. Pat. No.5,151,092 to Buell; U.S. Pat. No. 5,221,274 to Buell; U.S. Pat. No.5,554,145 to Roe et al. on Sep. 10, 1996; U.S. Pat. No. 5,569,234 toBuell et al.; U.S. Pat. No. 5,580,411 to Nease et al.; U.S. Pat. No.6,004,306 to Robles et al.; U.S. Pat. No. 5,938,648 to LaVon et al.;U.S. Pat. No. 5,865,823 to Curro; U.S. Pat. No. 5,571,096 to Dobrin etal.; U.S. Pat. No. 5,518,801 to Chappell, et al.; U.S. Pat. 4,573,986 toMinetola et al.; U.S. Pat. No. 3,929,135, to Thompson; U.S. Pat. No.4,463,045 to Ahr, et al.; U.S. Pat. No. 4,609,518 to Curro et al.; U.S.Pat. No. 4,629,643 to Curro et al.; U.S. Pat. No. 5,037,416 to Allen etal.; U.S. Pat. No. 5,269,775 to Freeland et al.; U.S. Pat. 4,610,678 toWeisman et al.; U.S. Pat. 4,673,402 to Weisman et al.; U.S. Pat.4,888,231 to Angstadt; U.S. Pat. No. 5,342,338 to Roe; U.S. Pat. No.5,260,345 to DesMarais et al.; U.S. Pat. No. 5,026,364 to Robertson;U.S. Pat. 3,848,594 to Buell; U.S. Pat. 4,846,815 to Scripps; U.S. Pat.4,946,527 to Battrell; U.S. Pat. No. 4,963,140 to Robertson et al.; U.S.Pat. No. 4,699,622 to Toussant et al.; U.S. Pat. No. 5,591,152 to Buellet al.; U.S. Pat. 4,938,753 to Van Gompel, et al.; U.S. Pat. No.5,669,897 to LaVon, et al.; U.S. Pat. No. 4,808,178 to Aziz et al.; U.S.Pat. No. 4,909,803 to Aziz et al.: U.S. Pat. No. 4,695,278 to Lawson;U.S. Pat. No. 4,795,454 issued to Dragoo; U.S. Pat. Nos. 5,607,760 toRoe on; U.S. Pat. No. 5,609,587 to Roe; U.S. Pat. No. 5,635,191 to Roeet al.; U.S. Pat. No. 5,643,588 to Roe et al.; and U.S. Pat. No.5,968,025 to Roe et al.

[0039] The absorbent core 10 in FIG. 1 generally is disposed between thetopsheet 24 and the backsheet 26. The absorbent core typically comprisesa storage layer, which may be partially or totally surrounded by a corewrap. The storage layer may comprise any absorbent material that isgenerally compressible, conformable, non-irritating to the wearer'sskin, and capable of absorbing and retaining liquids such as urine andother certain body exudates. The storage layer may comprise a widevariety of liquid-absorbent materials commonly used in disposablediapers and other absorbent articles such as comminuted wood pulp, whichis generally referred to as air felt or fluff. Examples of othersuitable absorbent materials include creped cellulose wadding; meltblown polymers, including co-form; chemically stiffened, modified orcross-linked cellulosic fibers; tissue, including tissue wraps andtissue laminates, absorbent foams, absorbent sponges, superabsorbentpolymers (such as superabsorbent fibers), absorbent gelling materials,or any other known absorbent material or combinations of materials.Examples of some combinations of suitable absorbent materials are fluffwith absorbent gelling materials and/or superabsorbent polymers, andabsorbent gelling materials and superabsorbent fibers etc. In oneoptional embodiment the storage layer is air felt free, that is, itcontains no air felt. The storage layer may further comprise minoramounts (typically less than 10%) of non-liquid absorbent materials,such as adhesives, waxes, oils and the like.

[0040] Exemplary absorbent structures for use as the absorbentassemblies are described in U.S. Pat. No. 4,834,735, entitled “HighDensity Absorbent Members Having Lower Density and Lower Basis WeightAcquisition Zones”, issued to Alemany et al. on May 30, 1989; and U.S.Pat. No. 5,625,222 entitled “Absorbent Foam Materials For Aqueous FluidsMade From high Internal Phase Emulsions Having Very High Water-To-OilRatios” issued to DesMarais et al. on Jul. 22, 1997.

[0041] In one optional embodiment of the present invention the absorbentcore comprises, in addition to the storage layer and the durablehydrophilic core wrap, an acquisition system, which comprises an upperacquisition layer facing towards the wearer and a lower acquisitionlayer. In one preferred embodiment the upper acquisition layer comprisesa nonwoven fabric whereas the lower acquisition layer preferablycomprises a mixture of chemically stiffened, twisted and curled fibers,high surface area fibers and thermoplastic binding fibers. In anotherpreferred embodiment both acquisition layers are provided from anon-woven material, which is preferably hydrophilic. The acquisitionlayer preferably is in direct contact with the storage layer.Furthermore, the storage layer or parts thereof, such as the upperacquisition layer, may optionally be coated with the hydrophilicityboosting composition.

[0042] The durable, hydrophilic substantially liquid pervious topsheetof the present invention will preferably have a basis weight of betweenabout 5 grams per square meter (or gsm) and about 100 gsm, morepreferably between about 10 gsm and about 75 gsm, even more preferablybetween about 20 gsm and about 65 gsm.

[0043] Topsheet Substrate—The durable, hydrophilic substantially liquidpervious topsheet of the present invention comprises a topsheetsubstrate (substrate) which has been coated with a hydrophilicityboosting composition. The substrate of interest herein may comprise anyknown type of substrate, including but not limited to fabrics, garments,textiles, and films. In certain embodiments, the substrate may compriseone or more fibers. A fiber is defined as a fine hairlike structure, ofanimal, vegetable, mineral, or synthetic origin. Commercially availablefibers have diameters ranging from less than about 0.001 mm (about0.00004 in) to more than about 0.2 mm (about 0.008 in) and they come inseveral different forms: short fibers (known as staple, or chopped),continuous single fibers (filaments or monofilaments), untwisted bundlesof continuous filaments (tow), and twisted bundles of continuousfilaments (yam).

[0044] The substrate may comprise fibers made by nature (naturalfibers), made by man (synthetic or man-made), or combinations thereof.Example natural fibers include but are not limited to: animal fiberssuch as wool, silk, fur, and hair; vegetable fibers such as cellulose,cotton, flax, linen, and hemp; and certain naturally occurring mineralfibers. Synthetic fibers can be derived from natural fibers or not. Forexample synthetic fibers which are derived from natural fibers, includebut are not limited to, rayon and lyocell, both of which are derivedfrom cellulose. Synthetic fibers which are not derived from naturalfibers can be derived from other natural sources or from mineralsources. Exemplary synthetic fibers derived from natural sources,include but are not limited to, polysaccharides such as starch.Exemplary fibers from mineral sources, include but are not limited to,polyolefin fibers such as polypropylene and polyethylene fibers, whichare derived from petroleum, and silicate fibers such as glass andasbestos. Synthetic fibers are commonly formed, when possible, by fluidhandling processes (e.g., extruding, drawing, or spinning a fluid suchas a resin or a solution). Synthetic fibers are also formed by solidhandling size reduction processes (e.g., mechanical chopping or cuttingof a larger object such as a monolith, a film, or a fabric).

[0045] Examples of suitable synthetic fibers which may comprise all orpart of the topsheet wrap substrates of the present invention includebut are not limited, to nylon (polyamide), acrylic (polyacrylonitrile),aramid (aromatic polyamide), polyolefin (polyethylene andpolypropylene), polyester, butadiene-styrene block copolymers, naturalrubber, latex, spandex (polyurethane) and combinations thereof.

[0046] Synthetic fibers that contain more than one type of repeat unitcan result from combining repeat units at the molecular level withineach macromolecular strand (co-polymer), between macromolecular strands(homopolymer blends), or combinations thereof (co-polymer blends); orthey can result from combining repeat units at a higher scale level withdistinct nanoscopic, microscopic, or macroscopic phases (e.g.,multicomponent fibers). Each component of a multicomponent fiber cancomprise a homopolymer, a co-polymer, or blends thereof. Bicomponentfibers are common versions of multicomponent fibers. The two or moretypes of repeat units in a copolymer can be arranged randomly or inalternating blocks of each type. Blocks of different types of repeatunits can joined to one another at their respective ends (blockco-polymers) or between the respective end of at least one block (graftco-polymers).

[0047] Nonwoven materials are a type of fabric typically made fromfibers in a web format. Nonwoven materials are described by Butler I,Batra S K, et al, Nonwovens Fabrics Handbook, Association of theNonwoven Fabrics Industry, 1999, and by Vaughn E A, Nonwoven FabricSampler and Technology Reference, Association of the Nonwoven FabricsIndustry.

[0048] Substrates comprising nonwoven materials can be formed by directextrusion processes during which the fibers and the nonwoven materialsare formed at about the same point in time, or by preformed fibers whichcan be laid into nonwoven materials at a distinctly subsequent point intime. Exemplary direct extrusion processes include but are not limitedto: spunbonding, meltblowing, solvent spinning, electrospinning, andcombinations thereof typically forming layers. Exemplary “laying”processes include wetlaying and drylaying. Example drylaying processesinclude but are not limited to airlaying, carding, and combinationsthereof typically forming layers. Combinations of the above processesyield nonwovens commonly called hybrids or composites. Exemplarycombinations include but are not limited to spunbond-meltblown-spunbond(SMS), spunbond-carded (SC), spunbond-airlaid (SA), meltblown-airlaid(MA), and combinations thereof, typically in layers. Combinations whichinclude direct extrusion can be combined at the about the same point intime as the direct extrusion process (e.g., spinform and coform for SAand MA), or at a subsequent point in time. In the above examples, one ormore individual layers can be created by each process. For instance, SMScan mean a three layer, ‘sms’ nonwoven materials, a five layer ‘ssmms’nonwoven materials, or any reasonable variation thereof wherein thelower case letters designate individual layers and the upper caseletters designate the compilation of similar, adjacent layers.

[0049] The fibers in a nonwoven materials are typically joined to one ormore adjacent fibers at some of the overlapping junctions. This includesjoining fibers within each layer and joining fibers between layers whenthere is more than one layer. Fibers can be joined by mechanicalentanglement, by chemical bond or by combinations thereof.

[0050] Fibers and nonwoven materials can be subjected to additionaltreatment after formation. For nonwoven materials, additional treatmentcommonly occurs after the fibers are joined to one another(post-treatment). Examples of additional treatments include but are notlimited to mechanical stresses, chemical additives, or combinationsthereof.

[0051] It is also within the scope of the present invention that theterm “topsheet substrate” includes laminates of two or more substratesor webs. Commercially available laminates, or purpose built ones wouldalso be within the scope of the present invention. Additionally, thesubstrates may be flat or textured. The formation of textured substratesand laminates forms no part of this invention. The following discussionis for convenience of formulation, but is not intended to limit the typeof substrate used herein.

[0052] In one optional embodiment of the present invention the substrateis treated with a high-energy surface treatment. This high-energytreatment may be prior to or concurrent with the coating of thesubstrate with the hydrophilicity boosting composition. The high-energytreatment may be any suitable high-energy treatment for increasing thehydrophilicity of a substrate. Suitable high-energy treatments, includebut are not limited to, corona discharge treatment, plasma treatment, UVradiation, ion beam treatment, electron beam treatment and combinationsthereof.

[0053] High-energy surface treatments which increase surface energy areuseful in that in combination with the nanoparticles they can providethe surface with durable hydrophilic properties. In turn, increasedsurface energy increases the wettability of the substrate without use ofsurfactants in the dispersion to achieve wetting. Avoiding use ofsurfactant is useful for reasons previously discussed. In a non-limitingexample, corona treatment places transient charges on fibrousthermoplastic surfaces. As discussed earlier, partial or full chargesdissipate over time, and maintaining partial or full charges on fibrousthermoplastic surfaces is a common limitation. However, it has beenfound that corona treatment in combination with the nanoparticles can beused to place a durable charge on the material so that water continuesto be attracted to the material after time elapses. The use ofnanoparticles in conjunction with high-energy surface treatments, canconvert the transient properties of such treatments to more durableproperties. In a non-limiting example, corona treatment of a 13 gram persquare meter hydrophobic SMS polypropylene nonwoven subsequently treatedwith a hydrophilicity boosting compositions and dried exhibitedconsistently fast strikethrough following multiple gushes or insults.Without wishing to be bound by theory, the corona treatment increasedthe surface energy for the fiber. The hydrophilicity boostingcompositions without a surfactant was brought into contact with thefiber surfaces before the charges could dissipate. The higher surfaceenergy enabled the dispersion to wet the fibrous surfaces better thanwould have been possible without the corona treatment. On the surfaceswhich are wetted, the nanoparticles associate with the partial or fullcharge on the surface which would otherwise be transient. Thisassociation may take the form of a van der Waals interaction or the formof some other interaction or bond. The nanoparticles are sufficientlysmall to render the associations sufficient strong to withstand multiplestrikethroughs. The nanoparticle is sufficiently large to resistrotation away from oxygen into the polymer or dissipate in general.

[0054] Additional illustrative, but non limiting, information onmechanical entanglement and by chemical bonding of fiber, as well asadditional treatments to nonwoven material, such as high-energytreatment, may be found in copending U.S. Published patent applicationSer. No. 2002/0151634 (application Ser. No. 10/060,708) filed on Jan.30, 2002, published on Oct. 17, 2002, P&G Docket No. 8408M; U.S.Published patent application Ser. No. 2002/0192366 (application Ser. No.10/060,694) filed on Jan. 30, 2002, published on Dec. 19, 2002, P&GDocket No. 8837Q; U.S. Published patent application No. 2002/0150678(application Ser. No. 10/060582) filed on Jan. 30, 2002, published onOct. 17, 2002, P&G Docket No. 8838Q; U.S. patent application Ser. No.10/338,603 filed on Jan. 8, 2003, P&G Docket No. 8857; and U.S. patentapplication Ser. No. 10/338,610 filed on Jan. 8, 2003, P&G Docket No.8858.

[0055] The following patents may referred to for their disclosuresrelated to the substrate: U.S. Pat. No. 3,862,472 issued Jan. 28, 1975;U.S. Pat. No. 3,982,302 issued Sep. 28, 1976; U.S. Pat. No. 4,004,323issued Jan. 25, 1977; U.S. Pat. No. 4,057,669 issued Nov. 8, 1977; U.S.Pat. No. 4,097,965 issued Jul. 4, 1978; U.S. Pat. No. 4,176,427 issuedDec. 4, 1979; U.S. Pat. No. 4,130,915 issued Dec. 26, 1978; U.S. Pat.No. 4,135,024 issued Jan. 16, 1979; U.S. Pat. No. 4,189,896 issued Feb.26, 1980; U.S. Pat. No. 4,207,367 issued Jun. 10, 1980; U.S. Pat. No.4,296,161 issued Oct. 20, 1981; U.S. Pat. No. 4,309,469 issued Jan. 25,1982; U.S. Pat. No. 4,682,942 issued Jul. 28, 1987; and U.S. Pat. Nos.4,637,859; 5,223,096; 5,240,562; 5,556,509; and 5,580,423.

[0056] Hydrophilicity Boosting Composition—The hydrophilicity boostingcompositions of the present invention comprise a hydrophilicity boostingamount of nanoparticles. By hydrophilicity boosting amount, it isintended that an amount of nanoparticles be present in thehydrophilicity boosting compositions which are sufficient to make asubstrate to which it is applied more hydrophilic. Such amounts arereadily ascertained by one of ordinary skill in the art and are based onmany factors, including but not limited to, the substrate used, thenanoparticles used, the desired hydrophilicity of the durable,hydrophilic substantially liquid pervious topsheet, the consumer productin which the topsheet is used, etc. Preferably the nanoparticles arepresent in the hydrophilicity boosting compositions at levels of fromabout 0.0001% to about 20%, preferably from about 0.001% to about 15%,and more preferably from about 0.001% to about 10%, by weight of thecomposition.

[0057] Typically the amount of hydrophilicity boosting compositionspresent on a topsheet substrate will vary depending upon many factors,including but not limited to, the substrate used, the nanoparticlesused, the desired hydrophilicity of the durable, hydrophilicsubstantially liquid pervious topsheet, the consumer product in whichthe topsheet is used, etc. Preferably, the amount of hydrophilicityboosting compositions on the topsheet substrate will be presentinvention will be between about 0.01 grams of hydrophilicity boostingcomposition per square meter of substrate (or gsm substrate) and about30 gsm substrate, more preferably between about 0.01 gsm substrate andabout 20 gsm substrate, even more preferably between about 0.1 gsmsubstrate and about 10 gsm substrate. In one preferred embodiment of thepresent invention the nanoparticles are applied to the substrate as adispersion in a carrier.

[0058] Nanoparticles are particles which have a particle size, that isdiameter, which is of the order of magnitude of nanometers. That is,nanoparticles have a particle size ranging from about 1 to about 750nanometers. Such particles are technologically significant since theyare utilized to produce durable, hydrophilic substantially liquidpervious topsheet that have novel and useful properties due to the verysmall dimensions of their particulate constituents. Nanoparticles withparticle sizes ranging from about 2 nm to about 750 nm can beeconomically produced. Non-limiting examples of particle sizedistributions of the nanoparticles are those that fall within the rangefrom about 2 nm to less than about 750 nm, alternatively from about 2 nmto less than about 200 nm, and alternatively from about 2 nm to lessthan about 150 nm.

[0059] The particle size of the nanoparticles is the largest diameter ofa nanoparticle

[0060] The mean particle size of various types of nanoparticles maydiffer from the particle size distribution of the nanoparticlesparticles. For example, a layered synthetic silicate can have a meanparticle size of about 25 nanometers while its particle sizedistribution can generally vary between about 10 nm to about 40 nm. (Itshould be understood that the particle sizes that are described hereinare for particles when they are dispersed in an aqueous medium and themean particle size is based on the mean of the particle numberdistribution. Non-limiting examples of nanoparticles can includecrystalline or amorphous particles with a particle size from about 2 toabout 750 nanometers. Boehmite alumina can have an average particle sizedistribution from 2 to 750 nm.)

[0061] When the hydrophilicity boosting composition is present on thesubstrate it will typically be a substantially uniform coating. When thehydrophilicity boosting composition dries, for example any waterevaporates, the nanoparticles may aggregate together on the substrateforming larger particles, or even appear film like, depending upon theobservation method used. In any event, the application of ahydrophilicity boosting composition comprising nanoparticles, providesfor a uniform coat of the substrate.

[0062] Either organic or inorganic nanoparticles may be used in thehydrophilicity boosting composition of the present invention. Suitableorganic nanoparticle include, but are not limited to, nanolatexes. A“nanolatex”, as used herein, is a latex with particle sizes less than orequal to about 750 nm. A “latex” is a colloidal dispersion ofwater-insoluble polymer particles that are usually spherical in shape.Nanolatexes may be formed by emulsion polymerization. “Emulsionpolymerization” is a process in which monomers of the latex aredispersed in water using a surfactant to form a stable emulsion followedby polymerization. Particles are produced with can range in size fromabout 2 to about 600 nm.

[0063] While organic nanoparticles are within the scope of the presentinvention, inorganic nanoparticles are preferred. Inorganicnanoparticles generally exist as oxides, silicates, carbonates andhydroxides. Some layered clay minerals and inorganic metal oxides can beexamples of nanoparticles. The layered clay minerals suitable for use inthe present invention include those in the geological classes of thesmectites, the kaolins, the illites, the chlorites, the attapulgites andthe mixed layer clays. Typical examples of specific clays belonging tothese classes are the smectices, kaolins, illites, chlorites,attapulgites and mixed layer clays. Smectites, for example, includemontmorillonite, bentonite, pyrophyllite, hectorite, saponite,sauconite, nontronite, talc, beidellite, volchonskoite and vermiculite.Kaolins include kaolinite, dickite, nacrite, antigorite, anauxite,halloysite, indellite and chrysotile. Illites include bravaisite,muscovite, paragonite, phlogopite and biotite. Chlorites includecorrensite, penninite, donbassite, sudoite, pennine and clinochlore.Attapulgites include sepiolite and polygorskyte. Mixed layer claysinclude allevardite and vermiculitebiotite. Variants and isomorphicsubstitutions of these layered clay minerals offer unique applications.

[0064] Layered clay minerals may be either naturally occurring orsynthetic. An example of one non-limiting embodiment of the coatingcomposition uses natural or synthetic hectorites, montmorillonites andbentonites. Another embodiment uses the hectorites clays commerciallyavailable, and typical sources of commercial hectorites are theLAPONITEs™ from Southern Clay Products, Inc., U.S.A; Veegum Pro andVeegum F from R. T. Vanderbilt, U.S.A.; and the Barasyms, Macaloids andPropaloids from Baroid Division, National Read Comp., U.S.A.

[0065] In one preferred embodiment of the present invention thenanoparticles comprise a synthetic hectorite a lithium magnesiumsilicate. One such suitable lithium magnesium silicate is LAPONIT™,which has the formula:

[Mg_(w)Li_(x)Si₈O₂₀OH_(4−y)F_(y)]^(z−)

[0066] wherein w=3 to 6, x=0 to 3, y=0 to 4, z=12−2w−x, and the overallnegative lattice charge is balanced by counter-ions; and wherein thecounter-ions are selected from the group consisting of selected Na⁺, K⁺,NH₄ ⁺, Cs⁺, Li⁺, Mg⁺⁺, Ca⁺⁺, Ba⁺⁺, N(CH₃)₄ ⁺ and mixtures thereof. (Ifthe LAPONITE™ is “modified” with a cationic organic compound, then the“counter-ion” could be viewed as being any cationic organic group (R).)

[0067] Other suitable synthetic hectorites include, but are not limitedto isomorphous substitutions of LAPONITE™, such as, LAPONITE B™,LAPONITE S™, LAPONITE XLS™, LAPONITE RD™, LAPONITE XLG™, and LAPONITERDS™.

[0068] The nanoparticles may also be other inorganic materials,including inorganic oxides such as, but not limited to, titanium oxidesilica, zirconium oxide, aluminum oxide, magnesium oxide andcombinations thereof. Other suitable inorganic oxides include variousinorganic oxides of alumina and silica.

[0069] In one preferred embodiment of the present invention thenanoparticles comprise a Boehmite alumina ([Al(O)(OH)]_(n)) which is awater dispersible, inorganic metal oxide that can be prepared to have avariety of particle sizes or range of particle sizes, including a meanparticle size distribution from about 2 nm to less than or equal toabout 750 nm. For example, a boehmite alumina nanoparticle with a meanparticle size distribution of around 25 nm under the trade name DisperalP2™ and a nanoparticle with a mean particle size distribution of around140 nm under the trade name of Dispal® 14N4-25 are available from NorthAmerican Sasol, Inc.

[0070] Use of mixtures of nanoparticles in the hydrophilicity boostingcompositions is also within the scope of the present invention.

[0071] In one preferred embodiment of the present invention thenanoparticles are selected from the group consisting of titaniumdioxide, Boehmite alumina, sodium magnesium lithium fluorosilicates andcombinations thereof.

[0072] Optional ingredients—The hydrophilicity boosting compositions ofthe present invention may also include optional ingredients such as, acarrier, surfactant and adjunct ingredients.

[0073] Optional ingredients, when present, are typically employed incompositions at levels of from about 0.001% to about 99.9%, preferablyfrom about 0.01% to about 98%, and more preferably from about 0.1% toabout 96%, by weight of the composition.

[0074] Suitable carriers include liquids, solids and gases. Onepreferred carrier is water, which can be distilled, deionized, or tapwater. Water is valuable due to its low cost, availability, safety, andcompatibility.

[0075] Optionally, in addition to or in place of water, the carrier cancomprise a low molecular weight organic solvent. Preferably, the solventis highly soluble in water, e.g., ethanol, methanol, acetone, ethyleneglycol, propanol, isopropanol, and the like, and mixtures thereof. Lowmolecular weight alcohols can reduce the surface tension of thenanoparticle dispersion to improve wettability of the substrate. This isparticularly helpful when the substrate is hydrophobic. Low molecularweight alcohols can also help the treated substrate to dry faster. Theoptional water soluble low molecular weight solvent can be used at anysuitable level. The carrier can comprise any suitable amount of thecomposition, including but not limited to from about 10% to about 99%,alternatively from about 30% to about 95%, by weight of the coatingcomposition.

[0076] Surfactants are an optional ingredient in some embodiments of thepresent invention. Surfactants are especially useful in the coatingcomposition as wetting agents to facilitate the dispersion ofnanoparticles onto the substrate. Surfactants are preferably includedwhen the coating composition is used to treat a hydrophobic substrate.

[0077] Suitable surfactants can be selected from the group includinganionic surfactants, cationic surfactants, nonionic surfactants,amphoteric surfactants, ampholytic surfactants, zwitterionic surfactantsand mixtures thereof. Nonlimiting examples of surfactants useful in thecompositions of the present invention are disclosed in McCutcheon's,Detergents and Emulsifiers, North American edition (1986), published byAllured Publishing Corporation; McCutcheon's, Functional Materials,North American Edition (1992); U.S. Pat. Nos. 5,707,950 and 5,576,282;and U.S. Pat. No. 3,929,678, to Laughlin et al., issued Dec. 30, 1975.

[0078] When a surfactant is used in the coating composition, it may beadded at an effective amount to provide facilitate application of thecoating composition. Surfactant, when present, is typically employed incompositions at levels of from about 0.0001% to about 60%, preferablyfrom about 0.001% to about 35%, and more preferably from about 0.001% toabout 25%, by weight of the composition.

[0079] Nonlimiting examples of surfactants, including preferred nonionicsurfactants, useful herein typically at levels from about 0.001% toabout 60%, by weight, include nonionic and amphoteric surfactants suchas the C₁₂-C₁₈ alkyl ethoxylates (“AE”) including the so-called narrowpeaked alkyl ethoxylates and C₆-C₁₂ alkyl phenol alkoxylates (especiallyethoxylates and mixed ethoxy/propoxy), C₁₂-C₁₈ betaines andsulfobetaines (“sultaines”), C₁₀-C₁₈ amine oxides, and the like.

[0080] Another class of useful surfactants is silicone surfactantsand/or silicones. They can be used alone and/or alternatively incombination with the alkyl ethoxylate surfactants described herein.Nonlimiting examples of silicone surfactants are the polyalkylene oxidepolysiloxanes having a dimethyl polysiloxane hydrophobic moiety and oneor more hydrophilic polyalkylene side chains, and having the generalformula:

R¹—(CH₃)₂SiO—(CH₃)₂SiO]_(a)—[(CH₃)(R¹)SiO]_(b)—Si(CH₃)₂—R¹

[0081] wherein a+b are from about 1 to about 50, and each R¹ is the sameor different and is selected from the group consisting of methyl and apoly(ethyleneoxide/propyleneoxide) copolymer group having the generalformula: —(CH₂)_(n)O(C₂H₄O)_(c)(C₃H₆O)_(d)R², wherein n is 3 or 4; totalc (for all polyalkyleneoxy side groups) has a value of from 1 to about100, alternatively from about 6 to about 100; total d is from 0 to about14; alternatively d is 0; total c+d has a value of from about 5 to about150, alternatively from about 9 to about 100 and each R² is the same ordifferent and is selected from the group consisting of hydrogen, analkyl having 1 to 4 carbon atoms, and an acetyl group, alternativelyhydrogen and methyl group. Each polyalkylene oxide polysiloxane has atleast one R¹ group being a poly(ethyleneoxide/propyleneoxide) copolymergroup. Silicone superwetting agents are available from Dow Coming assilicone glycol copolymers (e.g., Q2-5211 and Q2-5212).

[0082] It is also within the scope of the present invention to use amixture of surfactants.

[0083] Adjunct ingredients—The compositions can contain other optionaladjunct ingredients, including but not limited to process aids,antimicrobial preservatives, antioxidants, anti-static agents, chelatingagents, colorants, dyes, filler salts, fungicides, insect and mothrepellant agents, germicides, hydrotropes, metallic salts. Theseoptional ingredients may be included at any desired level, but aretypically added at a level of from about 0.0001% to about 99.99% byweight of the composition.

[0084] Applying the hydrophilicity boosting composition to thesubstrate—The hydrophilicity boosting composition can be applied to thesubstrate in any suitable manner. The hydrophilicity boostingcomposition can be applied to the substrate when the substrate is atleast partially immersed in a bath of the composition (immersiveprocesses), or without immersing the substrate in the coatingcomposition (non-immersive processes).

[0085] In one embodiment of the present invention the hydrophilicityboosting composition is applied by kiss-roll coating. In kiss-rollcoating, the composition is kept in a suitable bath. A rotating cylinderor any other device suitable for this process, is contacting thecomposition with at least a part of its surface. Thus, the compositionis spread on the surface of the cylinder. The substrate is brought intocontact with the cylinder while the cylinder already has the compositionspread on its surface. In this process, the amount of compositionapplied on the substrate can be controlled easily and it is possible toavoid soaking the substrate with composition.

[0086] Alternatively to the kiss-roll coating, the composition can alsobe sprayed on the surface of the plurality of fibers. Like the kiss-rollcoating, spraying enables low and easily controllable add-on level ofaqueous solution, which is preferred in the present invention. Otheralternative methods include, but are not limited to, printing such as,rotary, gravure, flexographic printing, ink jet printing, slot coatingand the like.

[0087] Process for Making a Disposable Absorbent Article—FIG. 2illustrates one optional embodiment of manufacturing a disposableabsorbent article. From dispensing roller 110 a backsheet 26 isdispensed onto a conveyer belt 120. The backsheet 26 moves along theconveyer belt 120 to a point 130 where the components of absorbent core10 are dispensed from bins 140 and 150. Air felt 160 dispensed from bin150 mixes with absorbent gelling material 170 prior to deposition on thehydrophilic backsheet 26 at point 130.

[0088] At stage 170 a portion of the durable, hydrophilic substantiallyliquid pervious topsheet 24 is placed over the absorbent core 10 andbacksheet 26. The durable, hydrophilic substantially liquid pervioustopsheet 24 was previously formed by coating a substrate with ahydrophilicity boosting composition. Lastly, at stage 180 the liquidpervious topsheet 24 is joined to the absorbent core 10 and/or backsheet26. Suitable methods of sealing include, but are not limited to,adhesive, heat, ultrasonic and combinations thereof. The formeddisposable absorbent article may then be further processed toincorporate additional features, such as leg gaskets, lotion etc.

EXAMPLES

[0089] Hydrophilicity boosting compositions, according to the presentinvention, are prepared as follows: % Wt of Component Component 1 2 3 45 6 7 8 9 10 11 12 13 Nanoparticle¹ 0.1 0.05 0.05 0.1 1 Nanoparticle²0.1 0.05 0.05 0.1 Nanoparticle³ 1 1 4 Nanoparticle⁴ 1 Surfactant⁵ 0.0750.075 0.075 0.075 0.075 0.075 Surfactant⁶ 0.025 0.025 Water quantitysufficient to 100%

[0090] Test Methods—Unless otherwise stated, all tests are performedunder standard laboratory conditions (50% humidity and at 73° F. (23°C.)).

[0091] Contact Angle—Dynamic contact angles are measured using theFTA200 Dynamic Contact Angle Analyzer, made by First Ten Angstroms, USA.A single drop of test solution is dispensed onto the sample substrate. Adigital video recording is made while the drop spreads out across thesurface of the substrate and the FTA200 software measures the contactangle of the liquid with the substrate as a function of time.

[0092] Determination of surface tension—The surface tension (unit: mN/m)is determined according to the following test. Apparatus: Equipment: K10tensiometer provided by Krüss GmbH, Germany or equivalent. The vesselelevation speed should be 4 mm/min. Liquid surface height should besensed automatically when using a plate or a ring. The equipment must beable to adjust the sample position automatically to the correct height.Precision of test should be +/−0.1 mN/m.

[0093] Procedure (i) Calibration: Pour 40 ml of saline (0.9 wt % NaCl indeionized water) into a cleaned beaker. Test the surface tension of thesaline with a platinum ring or a platinum plate using the methoddescribed in equipment instructions. The surface tension should be 71-72mN/m at 20° C. (ii) Method: Clean the beaker with deionized water andisopropanol, including burning it out with a gas burner for a fewseconds. Wait until the beaker temperature equilibrates to roomtemperature is reached. Place ten 60×60 mm pieces of test nonwoven intoa cleaned beaker. The nonwoven should have a basis weight of at least 10grams per square meter (or gsm). Add 40 ml of saline (0.9 wt % NaCl indeionized water) and stir by hand with a clean surfactant-free plasticstick for 10 seconds. Let the solution with nonwoven stand for 5minutes. Stir again by hand for ten seconds. Remove the nonwovens fromthe saline with a clean surfactant-free plastic stick. Let the solutionstand for ten minutes. Then test the liquids surface tension with aplatinum plate or platinum ring; using the method described in theequipment instructions. The measured surface tension is the wash-offsurface tension.

[0094] Liquid Strike-Through Test—The liquid strike-through time ismeasured using Lister-type strike-through equipment, manufactured byLenzing AG, Austria. Test procedure is based on standardized EDANA(European Disposables And Nonwovens Association) method 150.3-96, withthe test sample placed on an absorbent pad comprised of ten plies offilter paper (Ahlstrom Grade 632 obtained from Empirical ManufacturingCo., Inc., or equivalent). In a typical experiment, three consecutive 5ml gushes of test liquid (0.9% saline solution) are applied to anonwoven sample at one minute intervals and the respectivestrike-through times are recorded without changing the absorbent pad.

[0095] In addition to measuring the strike-through time for the firstgush, as described in the Edana Method, the test described below doesnot only measure the first gush but several subsequent gushes,especially the fifth gush.

[0096] Apparatus—Lister Strike-through Equipment—(i) A Funnel fittedwith magnetic valve: Rate of discharge of 25 ml in 3,5 (±0.25) seconds;(ii) A Strike-through plate: Constructed of 25 mm thick acrylic glass.The total weight of the plate must be 500 g. The electrodes should be ofnon-corrosive material. The electrodes are set in (4.0 mm×7.0 mm) crosssection grooves, cut in the base of the plate and fixed with quicksetting epoxy resin. FIGS. 3 4, and 5 illustrate a Strike-through plate200 containing electrodes 210. FIG. 3 is a top view of a Strike-throughplate 200, where as FIG. 4 is a sectional view along 4-4 of theStrike-through plate 200 of FIG. 3. FIG. 5 is a sectional perspectiveview along 5-5 of the Strike-through plate 200 of FIG. 3; (iii) Baseplate: A square of acrylic glass 125 mm×125 mm approximately; (iv) Ringstand to support the funnel; (v) Electronic Timer measuring to 0.01seconds; (vi) Burette with 50 ml capacity; and (vii) Core filter paperAhlstrom Grade 989 or equivalent (average Strike-through time 1.7 s+−0.3s, dimensions: 10×10 cm).

[0097] Procedure: (1) Carefully cut the required number of samples, 12.5cm×12.5 cm with touching the sample only at the edge of the sample. (2)Taking 10 plies of Core filter paper place one sample on the set of 10plies of filter paper on the base plate. The sample should be positionedon the filter paper in such a way that the side of the nonwoven, whichis intended to face the user's skin (when applied in an absorbentarticle) is uppermost. (3) Place the strike-through plate on top withthe center of the plate over the center of the test piece. Center theburette and the funnel over the plate. (4) Ensuring that the electrodesare connected to the timer, switch on the timer and set the clock tozero. (5) Fill the burette with saline solution (0.9 wt % NaCl indeionized water). (6) Keep the discharge valve of the funnel closed andrun 5.0 ml of liquid (=one gush) from the burette into the funnel. (7)Open the magnetic valve of the funnel to discharge 5.0 ml of liquid. Theinitial flow of liquid will complete the electrical circuit and startthe timer. It will stop when the liquid has penetrated into the pad andfallen below the level of the electrodes in the strike-through plate.(8) Record the time indicated on the electronic timer. (9) Wait 60seconds and repeat steps (4), and (6) to (9) for the second, the thirdgush and any subsequent gush, with each gush comprising 5 ml of liquid.(e.g., 5 ml into funnel, open magnetic valve, etc.) Record the Time forthe 1^(st), 2^(nd) and any subsequent gush in seconds.

[0098] Strike-through results for SMS polypropylene nonwoven materials(13 grams per square meter) exposed to a Laboratory Corona Treater(Model# BD-20AC, manufactured by Electro-Technic Products Inc., USA) andcoating compositions according to the present invention are reported inTable 2. TABLE 2 Strike-through Times Strike-through Time (seconds)Sample 1st Gush 2^(nd) Gush 5th Gush 0.2% Laponite RD (Southern 2.5 2.83.0 Clay Products) 0.1% Disperal P2 (Condea) 2.4 2.6 2.1

[0099] All documents cited in the Detailed Description of the Inventionare, in relevant part, incorporated herein by reference; the citation ofany document is not to be construed as an admission that it is prior artwith respect to the present invention.

[0100] While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A disposable absorbent article comprising adurable, hydrophilic substantially liquid pervious topsheet, saidsubstantially liquid pervious topsheet comprising: (a) a topsheetsubstrate; and (b) a hydrophilicity boosting composition coated on saidsubstrate, said hydrophilicity boosting composition comprising ahydrophilicity boosting amount of nanoparticles, wherein saidnanoparticles have a particle size of from about 1 to about 750nanometers.
 2. A disposable absorbent article according to claim 1wherein said substrate is selected from the group consisting of porouspolymeric films, nonwoven materials and combinations thereof.
 3. Adisposable absorbent article according to claim 2 wherein said nonwovenmaterial comprises fibers selected from the group consisting ofpolyolefins, polyesters, cellulose and combinations thereof.
 4. Adisposable absorbent article according to claim 3 wherein said nonwovenmaterial comprises fibers selected from the group consisting ofpolypropylene, polyethylene, polyethylene terepthalate, rayon andcombinations thereof.
 5. A disposable absorbent article according toclaim 1 wherein said nanoparticles are inorganic nanoparticles.
 6. Adisposable absorbent article according to claim 5 wherein saidnanoparticles are selected from the group consisting of titaniumdioxide, layered clay minerals, alumina oxide, silicates, andcombinations thereof.
 7. A disposable absorbent article according toclaim 6 wherein said nanoparticles are selected from the groupconsisting of titanium dioxide, Boehmite alumina, sodium magnesiumlithium fluorosilicates and combinations thereof.
 8. A disposableabsorbent article according to claim 1 wherein said hydrophilicityboosting composition further comprises a surfactant.
 9. A disposableabsorbent article according to claim 1 wherein said surfactant is anonionic surfactant.
 10. A disposable absorbent article according toclaim 1 wherein said storage layer comprises material selected from thegroup consisting of absorbent gelling material, fluff, and mixturesthereof.
 11. A disposable absorbent article according to claim 1 whereinsaid disposable absorbent article further comprises a substantiallyliquid impervious backsheet and an absorbent core, wherein saidabsorbent core is between said topsheet and said backsheet.
 12. Adisposable absorbent article according to claim 1 wherein saiddisposable absorbent article is selected from the group consisting ofdiapers, adult incontinence products, training pant, feminine hygienepads, and panty liners.
 13. A disposable absorbent article according toclaim 1 wherein said substrate has been treated with a high-energysurface treatment.
 14. A disposable absorbent article according to claim13 wherein said high-energy surface treatment is selected from the groupconsisting of corona discharge treatment, plasma treatment, UVradiation, ion beam treatment, electron beam treatment and combinationsthereof.
 15. A process for making a disposable absorbent articlecomprising a durable, hydrophilic substantially liquid pervioustopsheet, said process comprising the step of: coating a topsheetsubstrate with a hydrophilicity boosting composition, saidhydrophilicity boosting composition comprises a hydrophilicity boostingamount of nanoparticles, wherein said nanoparticles having a particlesize of from about 1 to about 750 nanometers.
 16. A process for making adisposable absorbent article according to claim 15 wherein prior to orconcurrent with coating of said substrate, said substrate is treatedwith a high energy surface treatment said high-energy surface treatmentis selected from the group consisting of corona discharge treatment,plasma treatment, UV radiation, ion beam treatment, electron beamtreatment and combinations thereof.
 17. A process for making adisposable absorbent article according to claim 15 whereinhydrophilicity boosting composition further comprises a carrier and asurfactant.
 18. A process for making a disposable absorbent articleaccording to claim 15 wherein said nanoparticles are inorganicnanoparticles.
 19. A process for making a disposable absorbent articleaccording to claim 15 wherein said substrate is selected from the groupconsisting of porous polymeric films, nonwoven materials andcombinations thereof.
 20. A process for making a disposable absorbentarticle according to claim 15 wherein said disposable absorbent articleis selected from the group consisting of diapers, adult incontinenceproducts, training pant, feminine hygiene pads, and panty liners.